Reformate control via accelerometer

Abstract

Engine surge includes oscillations in engine torque resulting in bucking or jerking motion of a vehicle that may degrade driver experience. The present application relates to increasing reformate entering an example engine cylinder in response to engine surge.

1. A method for an engine, comprising:
 reforming fuel at a catalyst into reformate; 
 adjusting a supply of reformate to a cylinder of the engine in response to an engine surge, the surge including an oscillation in torque produced by the engine; and 
 in response to surge:
 reducing in the cylinder at least one of charge dilution level and spark retard, and 
 increasing the supply of reformate to the cylinder of the engine. 
 
 
     
     
       2. The method of  claim 1 , further comprising increasing the supply of reformate to the cylinder of the engine in response to surge. 
     
     
       3. The method of  claim 1 , further comprising:
 sensing the oscillation in torque via an accelerometer sensor; and 
 band pass filtering torque oscillation frequencies above and below a surge window, where the engine surge includes engine torque oscillations having frequencies in the surge window. 
 
     
     
       4. The method of  claim 1 , further comprising increasing the supply of reformate to the cylinder of the engine in response to surge and a reformate amount in a reformate storage tank above a reformate threshold. 
     
     
       5. The method of  claim 1 , further comprising increasing the supply of reformate to the cylinder of the engine in response to surge and a rate of reformate production at the catalyst above a production threshold. 
     
     
       6. The method of  claim 1 , further comprising adjusting a wheel brake based on the accelerometer, and wherein the fuel includes ethanol. 
     
     
       7. A method for controlling ethanol-based reformate use in a vehicle engine, comprising:
 in a first decreased engine surge mode, supplying a first, lesser, charge reformate concentration to an engine cylinder, 
 in a second increased engine surge mode, supplying a second, greater, charge reformate concentration to the cylinder and adjusting a vehicle wheel brake in response to a longitudinal acceleration sensor of a stability control, the increased engine surge mode indicated by the longitudinal acceleration sensor. 
 
     
     
       8. The method of  claim 7 , where the second mode further includes band pass filtering engine torque oscillation frequencies above and below a surge window, the acceleration sensor detecting oscillations in the surge window. 
     
     
       9. The method of  claim 7 , further comprising, in response to a reformate amount in a reformate storage tank above a reformate threshold and a signal from the accelerometer indicating the engine surge state, transitioning from the first mode to the second mode. 
     
     
       10. The method of  claim 7 , further comprising, in response to a rate of reformate production at the catalyst above a production threshold and a signal from the accelerometer indicating the engine surge state, transitioning from the first mode to the second mode. 
     
     
       11. The method of  claim 7 , where the second mode includes reducing charge dilution in the cylinder of the engine. 
     
     
       12. The method of  claim 7 , where the second mode includes advancing spark timing. 
     
     
       13. The method of  claim 7 , further comprising, transitioning from the second mode to the first mode in response to an intensity of engine torque oscillations in a surge window below a surge threshold.